64 bit Windows does not support 16 bit InstallShield installation software.
See here for manual 64 bit install.
The MFC Development Tools used to build this
software do not support 64 bit. They
can not run in native 64 bit application space on a 64 bit Windows Swerver

32 bit carries on as normal. Feb 15, 2010.

Little known fact.
In 1991 I designed and implemented the very first version of Norton Antivirus, as a software developer for Peter Norton Inc, just after it was bought by Symantec.